Base catalyzed intramolecular transamidation of 2-aminoquinazoline derivatives on solid phase

A novel intramolecular cyclo-elimination via transamidation on the Rink Amide AM resin under mild basic conditions is presented. The methodology led to the synthesis of an important class of cardiotonic agents: imdiazo- and pyrimido-quinazolines from the corresponding 2-aminoquinazoline hydrobromide...

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Bibliographic Details
Published in:Tetrahedron 2005-05, Vol.61 (21), p.5011-5018
Main Authors: Grover, Rajesh K., Kesarwani, Amit P., Srivastava, Gaurav K., Kundu, Bijoy, Roy, Raja
Format: Article
Language:English
Subjects:
Imidazoquinazolinone
Pyrimidoquinazolinone
Solid-phase synthesis
Transamidation
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Summary:A novel intramolecular cyclo-elimination via transamidation on the Rink Amide AM resin under mild basic conditions is presented. The methodology led to the synthesis of an important class of cardiotonic agents: imdiazo- and pyrimido-quinazolines from the corresponding 2-aminoquinazoline hydrobromide salt under mild basic conditions. NMR based titration studies revealed the role of hydrobromide as a molecular switch, which on removal triggers the cyclisation of aminoquinazoline to tricyclic structures. The main advantage of transamidation under basic conditions over the TFA cleavage is the recyclability of the resin obtained after cyclo-elimination. This has been demonstrated by successive synthesis of four structurally diverse imidazoquianzolin-2-ones using the same batch of resin without any cross contamination. Graphical Abstract
ISSN:0040-4020
1464-5416
DOI:10.1016/j.tet.2005.03.047